improve sql parser

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlExprParser.java

@@ -22,7 +22,6 @@ import com.alibaba.druid.sql.ast.SQLOrderBy;
 import com.alibaba.druid.sql.ast.expr.SQLAggregateExpr;
 import com.alibaba.druid.sql.ast.expr.SQLBinaryOpExpr;
 import com.alibaba.druid.sql.ast.expr.SQLBinaryOperator;
-import com.alibaba.druid.sql.ast.expr.SQLBooleanExpr;
 import com.alibaba.druid.sql.ast.expr.SQLCharExpr;
 import com.alibaba.druid.sql.ast.expr.SQLHexExpr;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
@@ -484,6 +483,11 @@ public class MySqlExprParser extends SQLExprParser {
             lexer.nextToken();
             return userName;
         }
+        
+        if(lexer.token() == Token.ERROR) {
+            throw new ParserException("syntax error, token: " + lexer.token() + " " + lexer.stringVal() + ", pos : "
+                                      + lexer.pos());
+        }
 
         return super.primaryRest(expr);
     }

src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java

@@ -1239,6 +1239,14 @@ public class SQLEvalVisitorUtils {
                 return castToLong(list.get(0));
             }
         }
+        
+        if (val instanceof Boolean) {
+            if (((Boolean) val).booleanValue()) {
+                return 1l;
+            } else {
+                return 0l;
+            }
+        }
 
         return ((Number) val).longValue();
     }
@@ -1431,6 +1439,10 @@ public class SQLEvalVisitorUtils {
             return null;
         }
         
+        if(a == EVAL_VALUE_NULL || b == EVAL_VALUE_NULL) {
+            return null;
+        }
+        
         if (a instanceof String) {
             a = castToNumber((String) a);
         }

src/main/java/com/alibaba/druid/sql/visitor/functions/Char.java

@@ -42,8 +42,11 @@ public class Char implements Function {
                 int charCode = ((Number) paramValue).intValue();
                 buf.append((char) charCode);
             } else if (paramValue instanceof String) {
-                int charCode = new BigDecimal((String)paramValue).intValue();
-                buf.append((char) charCode);
+                try {
+                    int charCode = new BigDecimal((String) paramValue).intValue();
+                    buf.append((char) charCode);
+                } catch (NumberFormatException e) {
+                }
             } else {
                 return SQLEvalVisitor.EVAL_ERROR;
             }